The present invention relates to a gasket tab retainer. More particularly, the present invention relates to a multiple layer steel laminate gasket including at least two integral tabs formed in a metal layer of the gasket to locate and retain the gasket on a mating flange.
Gaskets are often used as seal between mating metal surfaces. One common application involves the placement of a gasket between a head and an exhaust manifold of an internal combustion engine. Another application involves gasket placement between the exhaust manifold and an exhaust pipe flange. Gaskets for either application can be considered high temperature gaskets and more particularly exhaust manifold gaskets since they provide an exhaust seal which prevents the byproducts of combustion exiting the engine from escaping into the engine compartment of a vehicle.
Exhaust manifold gaskets are typically installed by placing the gasket between an exhaust manifold and its mating component and aligning bolt holes or apertures formed in the gasket with corresponding holes formed in the manifold and mating component. Typically, a threaded fastener passes through the manifold and gasket and engages a corresponding threaded aperture formed in the mating component. Some maneuvering of the manifold and gasket relative to the mating component may be required to align the holes therein with the corresponding threaded apertures of the mating component before the fasteners can be inserted. However, during the assembly process, the gasket may slip from its desired position or drop off the end of the inserted fastener before it can be fixed in place between the exhaust manifold and its mating component.
Attempts have been made to retain a gasket against a mating component prior to and during assembly by providing separate clips for attaching the gasket to a gasket attaching portion of an engine part. Using such clips, a gasket is placed adjacent the mating component, and the separate clip is attached to the mating component such that the gasket is secured in place between the clip and the mating component. The separate clips typically include one end for contacting the gasket about an outer periphery thereof while a second end is attached to an outer periphery of a mating component or to an outer periphery of a connecting portion between mating components. Use of such separate clips does not eliminate the problems involved in the assembly process whereby a gasket may slip from its desired position. The clip attached to an outer periphery of the mating component may be jostled or become otherwise dislodged by contacting adjacent parts. Further, separate clips may become dislodged during sub-assembly handling and shipping of mating components, allowing the gasket to slip or drop. As a result, the gasket sealing portion may become offset or misaligned from the holes to be sealed before assembly, again requiring some maneuvering of the manifold and gasket relative to the mating component during assembly in order to achieve a tight seal. Assembly of a gasket to a mating flange using separate clips is also a complex operation, requiring multiple parts and means to hold the gasket adjacent the mating flange while the clips are attached. Finally, because such clips are designed to interact with an outer periphery of a gasket, the gasket itself must cover the full radial extent of a mating surface.
An exhaust manifold gasket for sealing between an exhaust header and a mating flange is provided that includes integral tabs formed on an outer periphery of the gasket to locate and retain the gasket on the mating flange. In accordance with the present invention, at least two tabs are integrally formed on an outer periphery of a metal layer of a multiple layer steel laminate gasket for attaching the gasket to a first mating flange. After the gasket is attached, the first mating flange to which the gasket is attached by the tabs is easily fixed to a second mating flange without supporting the gasket between the flanges.
The gasket of the present invention includes a metal layer having a length and a width, wherein the length is greater than the width. The metal layer constitutes at least a part of the gasket, and includes at least one hole formed therein corresponding to an exhaust gas flow hole in the first mating flange. A first outer periphery is defined by a radially outer edge of the first mating flange, while the gasket length and width defines a second outer periphery. The second outer periphery fits entirely within the first outer periphery. At least two tabs are integrally formed along the width of the layer, and are bent generally perpendicular relative to the rest of the gasket. The two tabs prevent the gasket from rotating relative to the mating flange after the gasket has been installed. The first mating flange further includes at least two apertures located within the first outer periphery that are sized and positioned to receive the tabs.
In one preferred embodiment, each tab comprises two contoured, resilient legs separated to form a vertical slot between the legs. Each tab leg further includes a contoured tip located at a distal end of each tab leg. The contoured tip includes a sloped portion that slopes laterally outwardly from the distal end of each tab leg along an outside edge of each tab leg. The sloped portion terminates in a laterally outwardly extending protrusion that creates an interference fit when inserted into the aperture. The vertical slot between the legs allows each leg to deform to adjust for aperture size tolerance.
Because the apertures are formed inside the configuration of the mating component, i.e. within the first outer periphery, a gasket formed according to the present invention uses less material, thereby reducing cost. The resilient tab legs deform when inserted into the corresponding apertures, such that insertion of the legs into corresponding apertures positively locates the gasket in place against the mating flange. Thus, the configuration of the resilient legs produces a tight interference fit within the apertures. The gasket is therefore held tightly in place by the tab legs. The tab legs are also positioned vertical to the width of the gasket, allowing for adjustment of the gasket relative to the mating flange to account for linear tolerances of the apertures and for gasket tolerances. Finally, the tabs are integral to a metal layer that comprises at least a portion of a gasket, so that manufacture is easily accomplished. Moreover, no separate clips are needed to positively locate the gasket adjacent a mating flange.
In a second preferred embodiment, each tab comprises a serrated side edge. The edge is oriented such that the tab may be easily inserted into a mating aperture. However, the edge digs into the inner periphery of the mating aperture upon attempted removal of the tab.
In accordance with a third embodiment, a two layer laminate gasket is disclosed having at least two mounting apertures. The gasket includes at least two tabs; each tab being integrally formed on an inner periphery of an aperture. The geometry and function of the tabs are substantially similar to those disclosed in the first two embodiments.